As various moving means such as bikes, bicycles, kickboards, and the like are popularized, many people are traveling on roads or walkways using such moving means. In the case of using such a moving means, it is necessary to wear a protective helmet for safety, and in some moving means, it is mandatory to wear a protective helmet by law.
However, such a protective helmet has only a secondary user protection function that relieves a shock when a user collides with a vehicle, an obstacle, a pedestrian, and does not provide a function of predicting an accident in advance to notify or prevent the accident, so that the function is quite limited. In addition, when a user wears a protective helmet, the user's field of view is limited so that the range of observing or predicting various risks/collisions that may occur during travelling is limited.